I have a kryptonite U lock and lately it's been sticking a lot while trying to turn the key. Usually I can eventually get the key turned. It was getting worse though and a few days ago I (unable to find any lube/wd-40 etc) cleaned it out with soap and water which seemed to help a great deal. I also started being very careful to make sure the little key-hole guard engaged. Last night when I was totally unable to get my bicycle unlocked and had to leave it there and walk home. The key would fit into the lock and turn half way and then stop. I'm going to go try and pick it up now, but I don't know the best way to try and make sure this doesn't keep happening. It's winter here and I wonder if that might have something to do with it.

Edit: I ended up at the hardware store and the guy there (who had built his own bike in his garage, conveniently) recommended jig-a-loo. This made the lock move really well but I still couldn't get it open. This is when I noticed that my key was twisted (From trying to force the lock probably). I flattened the key back in a clamp and was able eventually to unlock it, but I can't seem to lock it again, so I ordered new keys. I'll have to wait till they come to see if that solves anything or it's actually a problem with the lock...

My experience with "dry" teflon lube, such as finish line, has been excellent. I leave my lock outside locked to a rack 24/7. I had the exact problem you describe, and a generous amount of lube helped quite a bit. Eventually I also got around to spraying some speed degreaser in the keyhole, then relubing, and now the lock is good as new.
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Tal FishmanNov 19 '13 at 15:56

This all could have been avoided if you grease your locks once in a while. It helps a deal. An oz of prevention is better then a pound of cure.
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user10410Feb 26 '14 at 7:42

Great idea.. what do you recommended for grease in locks (esp given the comment above not to use oily liquids)
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DamonFeb 26 '14 at 15:06

Every locksmith I have ever met discourages using WD-40 in locks. It turns to gum.
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Ash MachineMar 2 '12 at 0:19

Well, a bike lock is a hair different from a standard lock, and I don't recommend WD40 as a lock lubricant, purely as a way to wash out whatever gunk may be clogging the mechanism.
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Daniel R HicksMar 2 '12 at 1:32

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My experiences with using TriFlow to both de-gunk and re-oil the cylinder in a Kryptonite U-lock has been very positive. It'll take quite a few drops, but it works a lot better than WD-40.
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moshbearApr 19 '13 at 11:33

@moshbear - The problem with TriFlow as a "degunker" is that it's "vehicle" is not a very good solvent. And there's also a slight danger that, if you use enough to fully "degunk" a badly gunked lock you could leave an excess of Teflon behind. But TriFlow is probably better than a lot of alternatives.
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Daniel R HicksApr 19 '13 at 18:28

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Thin wet lube for bike chains also works well in a pinch to get the lock moving smooth.
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BenzoJun 2 '13 at 15:09

I was told by a locksmith never to use graphite on locks that stay outdoors (like bike locks) because it mixes with air vapor and turns to mud inside the mechanism. He recommended spraying in a good dose of ether-based cleaner (e.g. electrical contact cleaner) and then a bunch of silicone lube after.

Keys totally wear out. I've had both a flat key and a tubular key break off in two separate U-locks. It's a pain. So as soon as the lock and key starts to get iffy, ether-clean the lock, lube it, and if it's still iffy, replace your key with a spare ASAP.

Also, as tempting as it is (and especially if you're irritated), NEVER force keys with pliers. That was my downfall with the breakage both times. I've learned to get good with an angle grinder metal cutoff wheel.

Graphite is best, but is preventative. Once it starts to jam up, you're not going to have much luck getting the graphite in there. LPS Greaseless lubricant works well once you're at that point. Avoid silicone lubes, they make a gooey sticky mess out of locks!

Because you put water in there it's probably frozen. I would recommend lock de-icer because it's alchohol based. It will also lubricated (for a short time) but more importantly it will help flush anything out of the lock and then it any leftover liquid will just evaporate.
Then I would put graphite in it or something teflon based. NOT WD-40 that stuff sucks for locks. It can be used to clean it although a locksmith will tell you not to do it.

If you go to a lock store or a local hardware store they might have a good suggestion but someone else mentioned sending it back on the lifetime warranty and that might be a good option for you as well.

Go to an automotive supply store and ask for lock deicer.It will melt any ice and lubricate the lock.Spray it in the key opening and rotate the key back and forth,try this several times applying more torque each time.It might help to let it sit awhile between applications.

my Kryptonite fagetaboutit wasn't opening. I lubricated it and tried all the keys and each was turning and the U-part jiggled back and forth but it didn't release. I used a small plastic needleless syringe to squirt some bike bio-chain cleaner up the key opening and after a couple minutes of it sitting in there the lock released. I think it cleaned out the gunk that was sticking the release mechanism. I then wiped out the ends where the U seats into, and tapped out any loose liquid, then lubricated keyhole and the nib that springs in and out. Works well now